Tellurian’s 2.4 Ghz Tranceiver Page
[http://store.qkits.com/category.cfm/RF]
This is a pretty spiffy little device. It is a tranceiver and can do full real time duplex RX / TX or it can receive on two seperate channels. It has 128 channels to pick from and an addressing space of 40 bits so it is possible to have many devices in the same air space and they will not stomp on each other. It also has an 8051 core built in so it will packetize your data, add RF headers and a CRC checksum for you. The receive side is in reverse, it will validate the address, and checksum and only notify you if the data is meant for you. Presto, very little for you to do but send or receive a serial stream. It even has a built in antenna, All this for only $16 CDN! (at QKits), a pretty decent deal I think.
[./roboticspgpag.html]
[http://www.tellurian.ca/resources/RF24G.c]
[http://www.sparkfun.com/commerce/categories.php]
I really like these modules, they are easy to use and reliable. I am using them for all of my designs now. My Bot91 robot uses this for telemetry and control. I am experiencing a very low error rate of under 0.01% bad packets (better than 1/10,000 ... often closer to 1/40000). However it operates in bluetooth range so bluetooth devices can clash (just change the channel then) and I have noticed that my microwave (if on) can corrupt packets, but generally it is a rock solid connection. It is easy to code, here is concise bit of sample code from SparkFun electronics. They are getting high error rates, but then it is only prototype code, but a good clear example of use.
This is the receiver or base unit that I made to use with the 2.4 Ghz tranceivers, it has one inside of course. I use it to monitor and log telemetry data from my robots and also to control them when testing or calibrating new algorithms or equipment. It has batteries built in so I can take it anywhere I take my robots. The keypad handles numeric entry, and a mini analog joystick can be used for directional control. It is very handy when Iam away from my PC. The range of the tranceivers is about 30m indoors, outdoor line of site is 150m. The human body seems to be the most significant RF blocking material. At the right is the base unit shown with its external antenna mounted in place.
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